ED

NAME

ed, red - text editor

SYNOPSIS

ed [-GVhs] [-p string] [file]

red [-GVhs] [-p string] [file]

DESCRIPTION

ed
is a line-oriented text editor.
It is used to create, display, modify and otherwise manipulate text
files.
red
is a restricted
ed:
it can only edit files in the current
directory and cannot execute shell commands.

If invoked with a
file
argument, then a copy of
file
is read into the editor's buffer.
Changes are made to this copy and not directly to
file
itself.
Upon quitting
ed,
any changes not explicitly saved with a
`w'
command are lost.

Editing is done in two distinct modes:
command
and
input.
When first invoked,
ed
is in command mode.
In this mode commands are read from the standard input and
executed to manipulate the contents of the editor buffer.
A typical command might look like:

,s/old/new/g

which replaces all occurrences of the string
old
with
new.

When an input command, such as
`a'
(append),
`i'
(insert) or
`c'
(change), is given,
ed
enters input mode. This is the primary means
of adding text to a file.
In this mode, no commands are available;
instead, the standard input is written
directly to the editor buffer. Lines consist of text up to and
including a
newline
character.
Input mode is terminated by
entering a single period (.) on a line.

All
ed
commands operate on whole lines or ranges of lines; e.g.,
the
`d'
command deletes lines; the
`m'
command moves lines, and so on.
It is possible to modify only a portion of a line by means of replacement,
as in the example above. However even here, the
`s'
command is applied to whole lines at a time.

In general,
ed
commands consist of zero or more line addresses, followed by a single
character command and possibly additional parameters; i.e.,
commands have the structure:

[address [,address]]command[parameters]

The address(es) indicate the line or range of lines to be affected by the
command. If fewer addresses are given than the command accepts, then
default addresses are supplied.

OPTIONS

Suppresses diagnostics. This should be used if
ed's
standard input is from a script.

-p string

Specifies a command prompt. This may be toggled on and off with the
`P'
command.

file

Specifies the name of a file to read. If
file
is prefixed with a
bang (!), then it is interpreted as a shell command. In this case,
what is read is
the standard output of
file
executed via
sh(1).
To read a file whose name begins with a bang, prefix the
name with a backslash (\).
The default filename is set to
file
only if it is not prefixed with a bang.

LINE ADDRESSING

An address represents the number of a line in the buffer.
ed
maintains a
current address
which is
typically supplied to commands as the default address when none is specified.
When a file is first read, the current address is set to the last line
of the file. In general, the current address is set to the last line
affected by a command.

A line address is
constructed from one of the bases in the list below, optionally followed
by a numeric offset. The offset may include any combination
of digits, operators (i.e.
+
and
-)
and whitespace.
Addresses are read from left to right, and their values are computed
relative to the current address.

One exception to the rule that addresses represent line numbers is the
address
0
(zero).
This means "before the first line,"
and is legal wherever it makes sense.

An address range is two addresses separated either by a comma or
semicolon. The value of the first address in a range cannot exceed the
value of the the second. If only one address is given in a range, then
the second address is set to the given address. If an
n-tuple
of addresses is given where
n > 2,
then the corresponding range is determined by the last two addresses in
the
n-tuple.
If only one address is expected, then the last address is used.

Each address in a comma-delimited range is interpreted relative to the
current address. In a semicolon-delimited range, the first address is
used to set the current address, and the second address is interpreted
relative to the first.

The following address symbols are recognized.

.

The current line (address) in the buffer.

$

The last line in the buffer.

n

The
nth,
line in the buffer
where
n
is a number in the range
[0,$].

-

The previous line.
This is equivalent to
-1
and may be repeated with cumulative effect.

^n

The
nth
previous line, where
n
is a non-negative number.

+

The
next line.
This is equivalent to
+1
and may be repeated with cumulative effect.

whitespace n

+n

The
nth
next line, where
n
is a non-negative number.
Whitespace
followed by a number
n
is interpreted as
+n.

,

The first through last lines in the buffer. This is equivalent to
the address range
1,$.

;

The current through last lines in the buffer. This is equivalent to
the address range
.,$.

/re/

The
next line containing the regular expression
re.
The search wraps to the beginning of the buffer and continues down to the
current line, if necessary.
// repeats the last search.

?re?

The
previous line containing the regular expression
re.
The search wraps to the end of the buffer and continues up to the
current line, if necessary.
?? repeats the last search.

'lc

The
line previously marked by a
`k'
(mark) command, where
lc
is a lower case letter.

REGULAR EXPRESSIONS

Regular expressions are patterns used in selecting text.
For example, the
ed
command

g/string/

prints all lines containing
string.
Regular expressions are also
used by the
`s'
command for selecting old text to be replaced with new.

In addition to a specifying string literals, regular expressions can
represent
classes of strings. Strings thus represented are said to be matched
by the corresponding regular expression.
If it is possible for a regular expression
to match several strings in a line, then the left-most longest match is
the one selected.

The following symbols are used in constructing regular expressions:

c

Any character
c
not listed below, including `{', '}', `(', `)', `<' and `>',
matches itself.

Matches any single character in
char-class.
To include a `]'
in
char-class,
it must be the first character.
A range of characters may be specified by separating the end characters
of the range with a `-', e.g., `a-z' specifies the lower case characters.
The following literal expressions can also be used in
char-class
to specify sets of characters:

If `-' appears as the first or last
character of
char-class,
then it matches itself.
All other characters in
char-class
match themselves.

Patterns in
char-class
of the form:

[.col-elm.] or,
[=col-elm=]

where
col-elm
is a
collating element
are interpreted according to
locale(5)
(not currently supported).
See
regex(3)
for an explanation of these constructs.

[^char-class]

Matches any single character, other than newline, not in
char-class.
char-class
is defined
as above.

^

If `^' is the first character of a regular expression, then it
anchors the regular expression to the beginning of a line.
Otherwise, it matches itself.

$

If `$' is the last character of a regular expression, it
anchors the regular expression to the end of a line.
Otherwise, it matches itself.

\(re\)

Defines a (possibly null) subexpression
re.
Subexpressions may be nested.
A subsequent backreference of the form `\n', where
n
is a number in the range [1,9], expands to the text matched by the
nth
subexpression.
For example, the regular expression `\(a.c\)\1' matches the
string `abcabc', but not `abcadc'.
Subexpressions are ordered relative to
their left delimiter.

*

Matches the single character regular expression or subexpression
immediately preceding it zero or more times. If '*' is the first
character of a regular expression or subexpression, then it matches
itself. The `*' operator sometimes yields unexpected results.
For example, the regular expression `b*' matches the beginning of
the string `abbb', as opposed to the substring `bbb', since a null match
is the only left-most match.

\{n,m\}

\{n,\}

\{n\}

Matches the single character regular expression or subexpression
immediately preceding it at least
n
and at most
m
times.
If
m
is omitted, then it matches at least
n
times.
If the comma is also omitted, then it matches exactly
n
times. If any of these forms occurs first in a regular expression or
subexpression, then it is interpreted literally (i.e., the regular
expression `\{2\}' matches the string `{2}', and so on).

\<

\>

Anchors the single character regular expression or subexpression
immediately following it to the beginning (\<) or ending
(\>) of a word, i.e., in ASCII, a maximal string of alphanumeric
characters, including the underscore (_).

The following extended operators are preceded by a backslash (\) to
distinguish them from traditional
ed
syntax.

\`

\'

Unconditionally matches the beginning (\`) or ending (\') of a line.

\?

Optionally matches the single character regular expression or subexpression
immediately preceding it. For example, the regular expression `a[bd]\?c'
matches the strings `abc', `adc' and `ac'. If \? occurs at the beginning
of a regular expressions or subexpression, then it matches a literal `?'.

\+

Matches the single character regular expression or subexpression
immediately preceding it one or more times. So the regular expression
`a\+' is shorthand for `aa*'. If \+ occurs at the beginning of a
regular expression or subexpression, then it matches a literal `+'.

\b

Matches the beginning or ending (null string) of a word. Thus the regular
expression `\bhello\b' is equivalent to `\<hello\>'. However, `\b\b'
is a valid regular expression whereas `\<\>' is not.

\B

Matches (a null string) inside a word.

\w

Matches any character in a word.

\W

Matches any character not in a word.

COMMANDS

All
ed
commands are single characters, though some require additional parameters.
If a command's parameters extend over several lines, then
each line except for the last
must be terminated with a backslash (\).

In general, at most one command is allowed per line.
However, most commands accept a print suffix, which is any of
`p'
(print),
`l'
(list) ,
or
`n'
(enumerate),
to print the last line affected by the command.

An interrupt (typically ^C) has the effect of aborting the current command
and returning the editor to command mode.

ed
recognizes the following commands. The commands are shown together with
the default address or address range supplied if none is
specified (in parenthesis).

(.)a

Appends text to the buffer after the addressed line, which may be the
address 0 (zero). Text is entered in input mode. The current address is
set to last line entered.

(.,.)c

Changes lines in the buffer. The addressed lines are deleted
from the buffer, and text is appended in their place.
Text is entered in input mode.
The current address is set to last line entered.

(.,.)d

Deletes the addressed lines from the buffer.
If there is a line after the deleted range, then the current address is set
to this line. Otherwise the current address is set to the line
before the deleted range.

e file

Edits
file,
and sets the default filename.
If
file
is not specified, then the default filename is used.
Any lines in the buffer are deleted before
the new file is read.
The current address is set to the last line read.

e !command

Edits the standard output of
`!command',
(see
!command
below).
The default filename is unchanged.
Any lines in the buffer are deleted before the output of
command
is read.
The current address is set to the last line read.

E file

Edits
file
unconditionally.
This is similar to the
e
command,
except that unwritten changes are discarded without warning.
The current address is set to the last line read.

f file

Sets the default filename to
file.
If
file
is not specified, then the default unescaped filename is printed.

(1,$)g/re/command-list

Applies
command-list
to each of the addressed lines matching a regular expression
re.
The current address is set to the
line currently matched before
command-list
is executed.
At the end of the
`g'
command, the current address is set to the last line affected by
command-list.

Each command in
command-list
must be on a separate line,
and every line except for the last must be terminated by a backslash
(\).
Any commands are allowed, except for
`g',
`G',
`v',
and
`V'.
A newline alone in
command-list
is equivalent to a
`p'
command.

(1,$)G/re/

Interactively edits the addressed lines matching a regular expression
re.
For each matching line,
the line is printed,
the current address is set,
and the user is prompted to enter a
command-list.
At the end of the
`G'
command, the current address
is set to the last line affected by (the last)
command-list.

The format of
command-list
is the same as that of the
`g'
command. A newline alone acts as a null command list.
A single `&' repeats the last non-null command list.

H

Toggles the printing of error explanations.
By default, explanations are not printed.
It is recommended that ed scripts begin with this command to
aid in debugging.

h

Prints an explanation of the last error.

(.)i

Inserts text in the buffer before the current line.
Text is entered in input mode.
The current address is set to the last line entered.

(.,.+1)j

Joins the addressed lines. The addressed lines are
deleted from the buffer and replaced by a single
line containing their joined text.
The current address is set to the resultant line.

(.)klc

Marks a line with a lower case letter
lc.
The line can then be addressed as
'lc
(i.e., a single quote followed by
lc
) in subsequent commands. The mark is not cleared until the line is
deleted or otherwise modified.

(.,.)l

Prints the addressed lines unambiguously. If invoked from a terminal,
ed
pauses at the end of each page until a newline is entered.
The current address is set to the last line printed.

(.,.)m(.)

Moves lines in the buffer. The addressed lines are moved to after the
right-hand destination address, which may be the address
0
(zero).
The current address is set to the
last line moved.

(.,.)n

Prints the addressed lines along with
their line numbers. The current address is set to the last line
printed.

(.,.)p

Prints the addressed lines. If invoked from a terminal,
ed
pauses at the end of each page until a newline is entered.
The current address is set to the last line
printed.

P

Toggles the command prompt on and off.
Unless a prompt was specified by with command-line option
-p string, the command prompt is by default turned off.

q

Quits ed.

Q

Quits ed unconditionally.
This is similar to the
q
command,
except that unwritten changes are discarded without warning.

($)r file

Reads
file
to after the addressed line. If
file
is not specified, then the default
filename is used. If there was no default filename prior to the command,
then the default filename is set to
file.
Otherwise, the default filename is unchanged.
The current address is set to the last line read.

($)r !command

Reads
to after the addressed line
the standard output of
`!command',
(see the
!command
below).
The default filename is unchanged.
The current address is set to the last line read.

(.,.)s/re/replacement/

(.,.)s/re/replacement/g

(.,.)s/re/replacement/n

Replaces text in the addressed lines
matching a regular expression
re
with
replacement.
By default, only the first match in each line is replaced.
If the
`g'
(global) suffix is given, then every match to be replaced.
The
`n'
suffix, where
n
is a positive number, causes only the
nth
match to be replaced.
It is an error if no substitutions are performed on any of the addressed
lines.
The current address is set the last line affected.

re
and
replacement
may be delimited by any character other than space and newline
(see the
`s'
command below).
If one or two of the last delimiters is omitted, then the last line
affected is printed as though the print suffix
`p'
were specified.

An unescaped `&' in
replacement
is replaced by the currently matched text.
The character sequence
`\m',
where
m
is a number in the range [1,9], is replaced by the
mth
backreference expression of the matched text.
If
replacement
consists of a single `%', then
replacement
from the last substitution is used.
Newlines may be embedded in
replacement
if they are escaped with a backslash (\).

(.,.)s

Repeats the last substitution.
This form of the
`s'
command accepts a count suffix
`n',
or any combination of the characters
`r',
`g',
and
`p'.
If a count suffix
`n'
is given, then only the
nth
match is replaced.
The
`r'
suffix causes
the regular expression of the last search to be used instead of the
that of the last substitution.
The
`g'
suffix toggles the global suffix of the last substitution.
The
`p'
suffix toggles the print suffix of the last substitution.
The current address is set to the last line affected.

(.,.)t(.)

Copies (i.e., transfers) the addressed lines to after the right-hand
destination address, which may be the address
0
(zero).
The current address is set to the last line
copied.

u

Undoes the last command and restores the current address
to what it was before the command.
The global commands
`g',
`G',
`v',
and
`V'.
are treated as a single command by undo.
`u'
is its own inverse.

(1,$)v/re/command-list

Applies
command-list
to each of the addressed lines not matching a regular expression
re.
This is similar to the
`g'
command.

(1,$)V/re/

Interactively edits the addressed lines not matching a regular expression
re.
This is similar to the
`G'
command.

(1,$)w file

Writes the addressed lines to
file.
Any previous contents of
file
is lost without warning.
If there is no default filename, then the default filename is set to
file,
otherwise it is unchanged. If no filename is specified, then the default
filename is used.
The current address is unchanged.

(1,$)wq file

Writes the addressed lines to
file,
and then executes a
`q'
command.

(1,$)w !command

Writes the addressed lines to the standard input of
`!command',
(see the
!command
below).
The default filename and current address are unchanged.

(1,$)W file

Appends the addressed lines to the end of
file.
This is similar to the
`w'
command, expect that the previous contents of file is not clobbered.
The current address is unchanged.

(.)x

Copies (puts) the contents of the cut buffer to after the addressed line.
The current address is set to the last line copied.

(.,.)y

Copies (yanks) the addressed lines to the cut buffer.
The cut buffer is overwritten by subsequent
`y',
`s',
`j',
`d',
or
`c'
commands.
The current address is unchanged.

(.+1)zn

Scrolls
n
lines at a time starting at addressed line. If
n
is not specified, then the current window size is used.
The current address is set to the last line printed.

!command

Executes
command
via
sh(1).
If the first character of
command
is `!', then it is replaced by text of the
previous
`!command'.
ed
does not process
command
for backslash (\) escapes.
However, an unescaped
`%'
is replaced by the default filename.
When the shell returns from execution, a `!'
is printed to the standard output.
The current line is unchanged.

(.,.)#

Begins a comment; the rest of the line, up to a newline, is ignored.
If a line address followed by a semicolon is given, then the
current address is set to that address. Otherwise, the current address
is unchanged.

($)=

Prints the line number of the addressed line.

(.+1)newline

Prints the addressed line, and sets the current address to
that line.

FILES

ed.hup

The file to which
ed
attempts to write the buffer if the terminal hangs up.

SEE ALSO

LIMITATIONS

ed
processes
file
arguments for backslash escapes, i.e., in a filename,
any characters preceded by a backslash (\) are
interpreted literally.

If a text (non-binary) file is not terminated by a newline character,
then
ed
appends one on reading/writing it. In the case of a binary file,
ed
does not append a newline on reading/writing.

per line overhead: 4 ints

DIAGNOSTICS

When an error occurs,
if
ed's
input is from a regular file or here document, then it
exits, otherwise it
prints a `?' and returns to command mode.
An explanation of the last error can be
printed with the
`h'
(help) command.

Attempting to quit
ed
or edit another file before writing a modified buffer
results in an error.
If the command is entered a second time, it succeeds,
but any changes to the buffer are lost.